The HIV/Hepatitis QUERI has been successful in using academic detailing, clinical reminders and audit and feedback strategies to increase VHA provider buy-in for routine HIV testing of all Veterans in primary care. Yet, it is not always readily known which providers are the key, critical change agents of an organization and thus, it is not known who should be targeted by implementation researchers for this detailing, reminders or feedback. One such way of finding these critical change agents is to undertake social network analyses of clinical providers prior to implementation efforts to identify which providers are consulted the most by their colleagues, viewed as trusted sources of information and perceived as credible, and therefore, people who can dissemination innovations through their social networks. However, no such social network implementation tool exists for widespread use to assist VHA implementation researchers with this endeavor. This proposed study addresses this gap by developing this implementation tool through a Hybrid Type 1 design. We will add a mixed-methods process evaluation to explore the social networks and relational coordination of providers who are currently participating in a VA randomized controlled trial to test the efficacy of two clinical interventions to improve Veterans' health outcomes: one intervention is the Mantram Repetition Program (MRP), the other is Present-Centered Therapy. Fifty-eight providers have referred 134 times to our study across the two study sites, Bedford VA and VA San Diego, but as there are 120 providers across both sites, many more have not referred at all. In exploring providers' social networks and how these impact their use of evidence and the process of discussing the RCT with colleagues in their network, we will draw on the Theory of Diffusion of Innovations to explore how interpersonal contacts within and between individual providers within VA services lines are important influences on the adoption of new behaviors. Our short-term goal is to conduct the tests of social networks' relationships to providers' behavior in our ongoing VA funded RCT through the addition of a Hybrid Type 1 effectiveness-implementation arm (this proposed RRP) involving a web-based survey with 80 providers at Bedford VA and VA San Diego, and face-to-face interviews with 40 of these same providers. Our long-term goal is to disseminate the social network implementation tool created from this study to cross- QUERI studies and QI activities with clinicians where we will further test and validate the tool we develop in this RRP to 1) understand the social networks of individuals with whom researchers are working with on an implementation project; 2) create implementation strategies for successful uptake based on where key individuals are located within the networks; 3) determine how social networks of providers may have changed or shifted during the course of implementation, 4) implement strategic social network interventions at the individual, segment (service line) or organizational level to create efforts to use social networks to generate social influence, accelerate behavior change and improve performance of sites, and 5) ensure sustainability of the intervention by creating rich social network implementation climates. We will test the following hypotheses: 1) Providers who referred Veteran patients to the RCT cluster together (are central ) in their social network compared to providers who did not refer to the RCT; 2) Providers who referred Veteran patients to the RCT are connected to bridgers in their social networks people who have influence across multiple social networks compared to providers who did not refer to the RCT; 3) Providers who referred Veteran patients to the RCT place a greater emphasis on communication and relationships with providers across their facility, compared to providers who did not refer.